In this era of guided missiles, the light touch of a young photographer's fertile imagination produced the winning photograph of one of this season's top passers, Don Allard of Boston College, tossing an Army Nike. An entry in a national contest for college football photographers sponsored annually by the College Sports Information Directors of America and judged by SPORTS ILLUSTRATED'S picture editor, Gerald Astor, the gag shot is the work of Peter Carroll (right), sophomore at B.C. and son of a veteran Associated Press photographer. By keeping the powerful scaffolding that supports the weapon out of camera range Carroll managed an allusion to the power threat that can be expected by all opponents of his home football team. The other winners in the contest, in six picture categories, are Ed Meador of Miami University of Ohio (for his picture of a ball carrier); Jim Laughead, University of Texas (quarterback in action); Ernest Robertson Jr., University of Tennessee (kicking); T/Sgt. Paul Hunter, Air Force Academy (center over ball); William R. Whitteker, University of Cincinnati (interior linemen); Elwood Smith, Temple University (pass catcher).